Within the food industry, it is common practice to pack liquid and partly liquid food products in packaging containers manufactured from a packaging laminate comprising a core layer of paper or paperboard and one or more barrier layers of, for example, polymer material or aluminium foil.
An increasingly common packaging type is the “carton bottle” manufactured in a filling machine in that packaging blanks of the above-described packaging laminate are formed and sealed as a sleeve. Said sleeve is closed in one end in that a top of thermoplastic material is injection moulded directly on the sleeve end portion. The sheets of packaging laminate may be cut from a magazine reel of packaging laminate.
When the top is finished the packaging container is ready to be filled with product through the still open bottom, and then sealed and finally folded. Before the filling operation the packaging container undergoes treatment. If distribution and storage is to be made in chilled temperature the packaging container is disinfected, whereas if distribution and storage is to be made in ambient temperature, the packaging container needs to be sterilized and the product needs to be processed so as to obtain sterility. Sterilization is a term referring to any process that eliminates or kills microbial life, including transmissible agents such as for example fungi, bacteria, viruses and spores, which may be present on a surface of the packaging material or in the product. Applied in the food packaging industry this is generally referred to as aseptic packaging, i.e. packaging sterilized products in sterilized packaging containers, i.e. keeping both the product and the packaging container free from living germs and microorganisms, so that the freshness of the product can be preserved without special cooling requirements, i.e. so that sterility can be maintained inside a packaging container although it is stored in ambient temperature. In the food packaging industry the term commercially sterile is also commonly used. According to Codex Alimentarius Commission ((WHO/FAO) CAC/RCP 40-1993) commercial sterility means “the absence of microorganisms capable of growing in the food at normal non-refrigerated conditions at which the food is likely to be held during manufacture, distribution and storage”.
A conventional way of sterilizing a ready-to-fill packaging container is to use hydrogen peroxide, preferably in gas phase.
Another way to sterilize such packaging containers is to irradiate it by means of a low voltage electron beam emitted from an electron beam emitter. An example of linear irradiation by electron beam of ready-to-fill packaging containers is disclosed in the international patent publication WO 2005/002973. The electron beam emitter is cylindrical with an electron exit window positioned at one of the distal ends. The packaging container is lifted to surround the electron beam emitter during the sterilization cycle. Other examples of irradiation of packaging containers, in these cases PET bottles, are described in for example WO 2011/011079 and EP 2 371 397. In the disclosed systems emitters are used having a diameter small enough to be passed through a neck portion of the bottles.